The expression of immune checkpoint proteins PD‐L1 and TIM3 in mouse and human head and neck squamous cell carcinoma

Abstract The aim of this study was to examine the expression of programmed death‐ligand 1 (PD‐L1) and of T cell immunoglobulin and mucin domain‐containing protein (TIM3) in oral epithelial dysplasia and head and neck squamous cell carcinoma (HNSCC). Mouse HNSCC was induced with 4‐nitroquinoline‐1 oxide (4NQO). Oral epithelial dysplastic lesions, carcinoma in situ and HNSCC lesions were stained with anti‐PD‐L1 and TIM3 antibodies. The expression of PD‐L1 and TIM3 in tumor cells and immune cells was semiquantitatively measured and compared. In parallel, human dysplasia and HNSCC were stained with anti‐PD‐L1 and anti‐TIM3. The expression pattern of PD‐L1 + and TIM3 + cells was further compared. In human and mouse samples both PD‐L1 and TIM3 were found to be expressed in neoplastic and immune cells in HNSCC, but not in dysplasia. There was no significant difference in PD‐L1 and TIM3 expression between metastatic and nonmetastatic HNSCC. We conclude that the 4NQO‐induced mouse HNSCC model may be an excellent preclinical model for immune checkpoint therapy.